Hydrophilic Coating

ABSTRACT

The invention relates to a hydrophilic coating formulation which when cured results in a hydrophilic coating, wherein the hydrophilic coating formulation comprises a polyelectrolyte and a non-ionic hydrophilic polymer. The invention further relates to a coating system, a hydrophilic coating, a lubricious coating, use of a polyelectrolyte and a non-ionic hydrophilic polymer in a lubricious coating, an article, a medical device or component and a method of forming on a substrate a hydrophilic coating.

This invention relates to a hydrophilic coating formulation which whencured results in a hydrophilic coating. The invention further relates toa coating system, a hydrophilic coating, a lubricious coating, use of apolyelectrolyte and a non-ionic hydrophilic polymer in a lubriciouscoating, an article, a medical device or component and a method offorming a hydrophilic coating on a substrate.

Many medical devices, such as urinary and cardiovascular catheters,syringes, and membranes need to have a lubricant applied to the outerand/or inner surface to facilitate insertion into and removal from thebody and/or to facilitate drainage of fluids from the body. Lubriciousproperties are also required so as to minimize soft tissue damage uponinsertion or removal. Especially, for lubrication purposes, such medicaldevices may have a hydrophilic surface coating or layer which becomeslubricious and attains low-friction properties upon wetting, i.e.applying a wetting fluid for a certain time period prior to insertion ofthe device into the body of a patient. A hydrophilic surface coating orlayer which becomes lubricious after wetting is hereinafter referred toas a hydrophilic coating. A coating obtained after wetting ishereinafter referred to as a lubricious coating.

A well-recognized problem encountered when using lubricious coatings hasbeen that the coatings may lose water and dry out prior to insertioninto the body, or in the body when it comes in contact with e.g. amucous membrane, such as when a urinary catheter is inserted into theurethra. Naturally, this affects the lubricity and low-frictionproperties of the lubricious coating, and may lead to pain and injuriesof the patient when the device is inserted into the body or removed fromthe body.

It would therefore be advantageous to have medical devices comprising ahydrophilic coating that stays lubricious upon applying a wetting fluidfor a prolonged period prior to and after insertion into the body of apatient. The time that the hydrophilic coating stays lubricious uponapplying a wetting fluid is herein further referred to as dry-out time.

It is an object of the present invention to provide a hydrophiliccoating that stays lubricious for a long time upon applying a wettingfluid before and after insertion into the body of a patient.

Surprisingly it has now been found that a lubricious coating with aprolonged and thereby improved dry-out time may be obtained when apolyelectrolyte and a non-ionic hydrophilic polymer are included in thehydrophilic coating from which said lubricious coating is formed byapplying a wetting fluid.

It has further been found that the water uptake rate is increased in acoating of the invention comprising a polyelectrolyte in combinationwith a non-ionic hydrophilic polymer, compared to a similar coatingwithout these components. This is in particular advantageous in case thearticle is stored with a dried coating and the coating is to be wettedprior to use. Satisfactory wetting of a coating, for instance of acatheter, may thus be accomplished within a few seconds after submersionin water or exposure to air with a relative humidity of 100%.

Within the context of the invention “lubricious” is defined as having aslippery surface. A coating on the outer or inner surface of a medicaldevice, such as a catheter, is considered lubricious if (when wetted) itcan be inserted into the intended body part without leading to injuriesand/or causing unacceptable levels of discomfort to the subject. Inparticular, a coating is considered lubricious if it has a friction asmeasured on a Harland FTS5000 Friction Tester (HFT) of 20 g or less,preferably of 15 g or less, at a clamp-force of 300 g, a pull speed of 1cm/s, a temperature of 22° C. and 35% relative humidity. The protocol isas indicated in the Examples.

The term “wetted” is generally known in the art and—in a broadsense—means “containing water”. In particular the term is used herein todescribe a coating that contains sufficient water to be lubricious. Interms of the water concentration, usually a wetted coating contains atleast 10 wt % of water, based on the dry weight of the coating,preferably at least 50 wt %, based on the dry weight of the coating,more preferably at least 100 wt % based on the dry weight of thecoating. For instance, in a particular embodiment of the invention awater uptake of about 300-500 wt % water is feasible. Examples ofwetting fluids are treated or untreated water, water-containing mixtureswith for example organic solvents or aqueous solutions comprising forexample salts, proteins or polysaccharides. In particular a wettingfluid can be a body fluid.

An important property of such lubricious coating is that they remainlubricious as long as needed. Therefore, the dry-out time should besufficiently long to allow application in medical devices. Within thecontext of the experiment, the dry-out time is the duration of thecoating remaining lubricious after a device comprising the lubriciouscoating has been taken out of the wetting fluid wherein it has beenstored and/or wetted. Dry-out time can be determined by measuring thefriction in gram as a function of time the catheter had been exposed toair on the HFT (see above). The dry-out time is the point in timewherein the friction reaches a value of 20 g or higher, or in a strictertest 15 g or higher as measured at a temperature of 22° C. and 35%relative humidity.

Within the context of the invention the term polymer is used for amolecule comprising two or more repeating units. In particular it may becomposed of two or more monomers which may be the same or different. Asused herein, the term includes oligomers and prepolymers. Usuallypolymers have a number average weight (Mn) of about 500 g/mol or more,in particular of about 1000 g/mol or more, although the Mn may be lowerin case the polymer is composed of relatively small monomeric units.Herein and hereinafter the Mn is defined as the Mn as determined bylight scattering.

Within the context of the invention a polyelectrolyte is understood tobe a high molecular weight linear, branched or crosslinked polymercomposed of macromolecules comprising constitutional units, in whichbetween 5 and 100% of the constitutional units contain ionized groupswhen the polyelectrolyte is in the lubricious coating. Herein aconstitutional unit is understood to be for example a repeating unit,for example a monomer. A polyelectrolyte herein may refer to one type ofpolyelectrolyte composed of one type of macromolecules, but it may alsorefer to two or more different types of polyelectrolytes composed ofdifferent types of macromolecules.

Considerations when selecting a suitable polyelectrolyte are itssolubility and viscosity in aqueous media, its molecular weight, itscharge density, its affinity with the supporting network of the coatingand its biocompatibility. Herein biocompatibility means biologicalcompatibility by not producing a toxic, injurous or immunologicalresponse in living mammalian tissue.

For a decreased migrateability, the polyelectrolyte is preferably apolymer having a weight average molecular weight of at least about 1000g/mol, as determinable by light scattering, optionally in combinationwith size exclusion chromatography. A relatively high molecular weightpolyelectrolyte is preferred for increasing the dry-out time and/orreduced migration out of the coating. The weight average molecularweight of the polyelectrolyte is preferably at least 20,000 g/mol, morepreferably at least 100,000 g/mol, even more preferably at least about150,000 g/mol, in particular about 200,000 g/mol or more. For ease ofapplying the coating it is preferred that the average weight is 1000,000g/mol or less, in particular 500,000 g/mol or less, more in particular300,000 g/mol or less.

Examples of ionized groups that may be present in the polyelectrolyteare ammonium groups, phosphonium groups, sulfonium groups, carboxylategroups, sulfate groups, sulfinic groups, sulfonic groups, phosphategroups, and phosphonic groups. Such groups are very effective in bindingwater. In one embodiment of the invention the polyelectrolyte alsocomprises metal ions. Metal ions, when dissolved in water, are complexedwith water molecules to form aqua ions [M(H₂O)_(x)]^(n+), wherein x isthe coordination number and n the charge of the metal ion, and aretherefore particularly effective in binding water. Metal ions that maybe present in the polyelectrolyte are for example alkali metal ions,such as Na⁺, Li⁺, or K⁺, or alkaline earth metal ions, such as Ca²⁺ andMg²⁺. In particular when the polyelectrolyte comprises quaternary aminesalts, for example quaternary ammonium groups, anions may be present.Such anions can for example be halogenides, such as Cl⁻, Br⁻, I⁻ and F⁻,and also sulphates, nitrates, carbonates and phosphates.

Suitable polyelectrolytes are for example salts of homo- and co-polymersof acrylic acid, salts of homo- and co-polymers of methacrylic acid,salts of homo- and co-polymers of maleic acid, salts of homo- andco-polymers of fumaric acid, salts of homo- and co-polymers of monomerscomprising sulfonic acid groups, homo- and co-polymers of monomerscomprising quarternary ammonium salts and mixtures and/or derivativesthereof. Examples of suitable polyelectrolytes arepoly(acrylamide-co-acrylic acid) salts, for examplepoly(acrylamide-co-acrylic acid) sodium salt,poly(acrylamide-co-methacrylic acid) salts, for examplepoly(acrylamide-co-methacrylic acid) sodium salt,poly(methacrylamide-co-acrylic acid) salts, for examplepoly(methacrylamide-co-acrylic acid) sodium salt,poly(methacrylamide-co-methacrylic acid) salts, for examplepoly(methacrylamide-co-methacrylic acid) sodium salt poly(acrylic acid)salts, for example poly(acrylic acid) sodium salt, poly(methacrylicacid) salts, for example poly(methacrylic acid) sodium salt,poly(acrylic acid-co-maleic acid) salts, for example poly(acrylicacid-co-maleic acid) sodium salt, poly(methacrylic acid-co-maleic acid)salts, for example poly(methacrylic acid-co-maleic acid) sodium salt,poly(acrylamide-co-maleic acid) salts, for examplepoly(acrylamide-co-maleic acid) sodium salt,poly(methacrylamide-co-maleic acid) salts, for examplepoly(methacrylamide-co-maleic acid) sodium salt,poly(acrylamido-2-methyl-1-propanesulfonic acid) salts, poly(4-styrenesulfonic acid) salts, poly(acrylamide-co-dialkyl ammonium chloride),quaternizedpoly[bis-(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea],polyallylammonium phosphate, poly(diallyldimethylammonium chloride),poly(sodium trimethyleneoxyethylene sulfonate),poly(dimethyldodecyl(2-acrylamidoethyl) ammonium bromide), poly(2-Nmethylpyridiniumethylene iodine), polyvinylsulfonic acids, and salts ofpoly(vinyl)pyridines, polyethyleneimines, and polylysines.

Particularly suitable polyelectrolytes for use in the current inventionare copolymeric polyelectrolytes, wherein said copolymericpolyelectrolyte is a copolymer comprising at least two different typesof constitutional units, wherein at least one type of constitutionalunits comprises ionizable or ionized groups and at least one type ofconstitutional units is absent of ionizable or ionized groups.

Ionizable is understood to be ionizable in neutral aqueous solutions,i.e. solutions having a pH between 6 and 8.

Said copolymeric polyelectrolyte may be a random or block copolymer.Generally, between 5 and 99 wt %, preferably between 50 and 90 wt %,more preferably between 70 and 85 wt % of the constitutional unitscomprise ionizable or ionized groups. In the lubricious coating, i.e.after wetting the hydrophilic coating, said ionizable groups may beionized or non-ionized. Typically between 1 and 100 wt % of the totalamount of ionizable and ionized groups is ionized when the copolymericpolyelectrolyte is in the lubricious coating, preferably between 30 and100 wt %, more preferably between 50 and 100 wt %, in particular between60 and 100 wt %.

Examples of constitutional units comprising ionizable groups areconstitutional units comprising carboxylic acid groups, for exampleacrylic acid, methacrylic acid, maleic acid, and formic acid; sulfonicacid groups; sulfinic acid groups; and phosphonic acid groups. Examplesof constitutional units comprising ionized groups are constitutionalunits comprising salts of the above mentioned ionizable groups, i.e.carboxylate groups, sulfonium groups, sulphinic groups, sulfate groups,phosphate groups, phosphonic groups, and phosphonium groups, andquaternary ammonium salts.

Examples of constitutional units that do not comprise ionizable groupsare acrylamide, methacrylamide, vinylalcohol, methylacrylate,methylmethacrylate, vinylpyrrolidone, and vinylcaprolactam.

Examples of said copolymeric polyelectrolytes arepoly(acrylamide-co-acrylic acid) salts, poly(acrylamide-co-methacrylicacid) salts, poly(methacrylamide-co-acrylic acid) salts,poly(methacrylamide-co-methacrylic acid) salts,poly(acrylamide-co-maleic acid) salts, poly(methacrylamide-co-maleicacid) salts, and poly(acrylamide-co-dialkyl ammonium chloride).Poly(acrylamide-co-acrylic acid) salts, for example the sodium salt, hasbeen found particularly suitable for obtaining a high lubricity anddry-out time.

The use of copolymeric polyelectrolytes comprising both constitutionalunits comprising ionizable or ionized groups and constitutional unitsabsent of ionizable or ionized groups has several advantages. Usuallysuch polyelectrolytes feature a higher solubility a particular solventsand less tendency to crystallize when used in the cured hydrophiliccoating.

A non-ionic hydrophilic polymer is understood to be a high molecularweight linear, branched or crosslinked polymer composed ofmacromolecules comprising constitutional units, in which less than 5,preferably less than 2% of the constitutional units contain ionizedgroups when the non-ionic hydrophilic polymer is in the lubriciouscoating. The non-ionic hydrophilic polymer is capable of providinghydrophilicity to a coating and may be synthetic or bio-derived and canbe blends or copolymers of both. The non-ionic hydrophilic polymersinclude but are not limited to poly(lactams), for examplepolyvinylpyrollidone (PVP), polyurethanes, homo- and copolymers ofacrylic and methacrylic acid, polyvinyl alcohol, polyvinylethers, maleicanhydride based copolymers, polyesters, vinylamines, polyethyleneimines,polyethyleneoxides, poly(carboxylic acids), polyamides, polyanhydrides,polyphosphazenes, cellulosics, for example methyl cellulose,carboxymethyl cellulose, hydroxymethyl cellulose, andhydroxypropylcellulose, heparin, dextran, polypeptides, for examplecollagens, fibrins, and elastin, polysaccharides, for example chitosan,hyaluronic acid, alginates, gelatin, and chitin, polyesters, for examplepolylactides, polyglycolides, and polycaprolactones, polypeptides, forexample collagen, albumin, oligo peptides, polypeptides, short chainpeptides, proteins, and oligonucleotides.

It has been found that adherence between the primer layer and thesurface of the article and/or the primer layer and the outer layer isimproved with increasing molecular weight of the functional non-ionichydrophilic polymer. Accordingly the weight average molecular weight ofthe functional non-ionic hydrophilic polymer, as determinable by asdetermined by light scattering, optionally in combination with sizeexclusion chromatography, is usually at least 20,000 g/mol, inparticular at least 55,000 g/mol, preferably at least 250,000 g/mol, inparticular at least 360,000 g/mol, more preferably at least 500,000g/mol, in particular at least 750,000 g/mol.

For practical reasons (ease of application and/or ease to realiseuniform coating thickness) the weight average molecular weight (Mw) isusually up to 10 million, preferably up to 5 million g/mol, morepreferably up to 3 million g/mol, most preferably up to 2 million g/mol,in particular up to 1.5 million g/mol, more in particular up to 1.3million g/mol, even more in particular up to 1 million g/mol.

In particular polyvinylpyrollidone (PVP) and polyethyleneoxide (PEO)having an Mw of at least 100000 g/mol have been found to have aparticular positive effect on lubricity and a low tendency to migrateout of the coating.

In particular for polyvinylpyrrolidone (PVP) and polymers of the sameclass, a polymer having a molecular weight corresponding to at leastK15, more in particular K30, even more in particular K80 is preferred.Particular good results have been achieved with a polymer having amolecular weight corresponding to at least K90. Regarding the upperlimit, a K120 or less, in particular a K100 is preferred. The K-value isthe value as determinable by the Method W1307, Revision 5/2001 of theViscotek Y501 automated relative viscometer. This manual may be found atwww.ispcorp.com/products/hairscin/index_(—)3.html

The invention relates to a hydrophilic coating formulation comprising apolyelectrolyte and a non-ionic hydrophilic polymer which when appliedto a substrate and cured results in a hydrophilic coating. Herein ahydrophilic coating formulation refers to a liquid hydrophilic coatingformulation, e.g. a solution or a dispersion comprising a liquid medium.Herein any liquid medium that allows application of the hydrophiliccoating formulation on a surface would suffice. Examples of liquid mediaare alcohols, like methanol, ethanol, propanal, butanol or respectiveisomers and aqueous mixtures thereof or acetone, methylethyl ketone,tetrahydrofuran, dichloromethane, toluene, and aqueous mixtures oremulsions thereof. The hydrophilic coating formulation further comprisescomponents which when cured are converted into the hydrophilic coating,and thus remain in the hydrophilic coating after curing. Herein curingis understood to refer to physical or chemical hardening or solidifyingby any method, for example heating, cooling, drying, crystallization orcuring as a result of a chemical reaction, such as radiation-curing orheat-curing. In the cured state all or part of the components in thehydrophilic coating formulation may be crosslinked forming covalentlinkages between all or part of the components, for example by using UVor electron beam radiation. However, in the cured state all or part ofthe components may also be ionically bonded, bonded by dipole-dipoletype interactions, or bonded via Van der Waals forces or hydrogen bonds.

The term “to cure” includes any way of treating the formulation suchthat it forms a firm or solid coating. In particular, the term includesa treatment whereby the hydrophilic polymer further polymerises, isprovided with grafts such that it forms a graft polymer and/or iscross-linked, such that it forms a cross-linked polymer.

The hydrophilic coating composition according to the invention typicallycomprises 1-90 wt %, preferably 3-50 wt %, more preferably 5-30 wt %, inparticular 10-20 wt % of polyelectrolyte based on the total weight ofthe dry coating.

The non-ionic hydrophilic polymer may be used in more than 1 wt % of thehydrophilic coating formulation, for example more than 10 wt %, morethan 20 wt %, or more than 30 weight %, based on the total weight of thedry coating. The non-ionic hydrophilic polymer can be present in thehydrophilic coating formulation up to 95 wt %, however, more often thenon-ionic hydrophilic polymer will be used up to 50, 60, 70 or 80 wt %,based on the total weight of the dry coating.

Hereinafter all percentages of components given in the application arebased on the total weight of the dry coating, i.e. the hydrophiliccoating formed upon curing the hydrophilic coating composition.

The invention also relates to a hydrophilic coating obtainable byapplying the hydrophilic coating formulation according to the inventionto a substrate and curing it. The invention further relates to alubricious coating obtainable by applying a wetting fluid to saidhydrophilic coating, and to the use of a polyelectrolyte and a non-ionichydrophilic polymer in a lubricious coating in order to improve itsdry-out time. Further the invention relates to an article, in particulara medical device or a medical device component comprising at least onehydrophilic coating according to the invention and to a method offorming on a substrate the hydrophilic coating according to theinvention.

In one embodiment of the invention the hydrophilic coating comprises thepolyelectrolyte and the non-ionic hydrophilic polymer. Said hydrophiliccoating is formed by curing a hydrophilic coating formulation comprisingthe polyelectrolyte and the non-ionic hydrophilic polymer. Preferablythe polyelectrolyte and the non-ionic hydrophilic polymer are covalentlyand/or physically bound to each other and/or entrapped to form a polymernetwork after curing.

In another embodiment of the invention the hydrophilic coating comprisesthe polyelectrolyte, the non-ionic hydrophilic polymer and a supportingnetwork, which may be a hydrophilic supporting network, and which isformed from a supporting monomer or polymer. Herein the supportingmonomer or polymer, apart from comprising a plurality of reactivemoieties capable of undergoing cross-linking reactions as describedbelow, may also contain hydrophilic functional groups. Said hydrophiliccoating is formed by curing a hydrophilic coating formulation comprisingthe polyelectrolyte, the non-ionic hydrophilic polymer and thesupporting monomer or polymer. Preferably the polyelectrolyte and/or thenon-ionic hydrophilic polymer and/or the hydrophilic supporting networkare covalently linked and/or physically bound to each other and/orentrapped to form a polymer network after curing.

These embodiments, wherein the polyelectrolyte and/or the non-ionichydrophilic polymer and/or the supporting monomer or polymer arecovalently and/or physically bound in the hydrophilic coating as part ofa polymer network, is particularly preferred since it has the advantagethat the polyelectrolyte and the non-ionic hydrophilic polymer will notleak out into the environment of the hydrophilic coating, for examplewhen it is coated on a medical device. This is particularly useful whenthe medical device is inside the human or animal body.

In the hydrophilic coating formulation which is used to produce saidhydrophilic coating, the weight ratio of non-ionic hydrophilic polymerto supporting monomer or polymer may for example vary between 10:90 and90:10, such as between 25:75 and 75:25 or such as between 60:40 and40:60.

A supporting network can be formed upon curing a supporting monomer orpolymer or any combination of supporting monomers and polymerscomprising a plurality of reactive moieties capable of undergoingcross-linking reactions, which may be present in the hydrophilic coatingformulation. The reactive moiety of the supporting monomer or polymermay be selected from the group consisting of radically reactive groups,such as alkenes, amino, amido, sulfhydryl (SH), unsaturated esters,ethers and amides, and alkyd/dry resins. The supporting monomer orpolymer may have a backbone and at least one of the above-mentionedreactive moieties. The backbone of the supporting polymer may beselected from the group consisting of polyethers, polyurethanes,polyethylenes, polypropylenes, polyvinyl chlorides, polyepoxides,polyamides, polyacrylamides, poly(meth)acrylics, polyoxazolidones,polyvinyl alcohols, polyethylene imines, polyesters like polyorthoestersand alkyd copolymers, polypeptides, or polysaccharides such as celluloseand starch or any combination of the above. In particular, a supportingmonomer, polymers with unsaturated esters, amides or ethers, thiol ormercaptan groups may suitably be used in the invention.

As used herein, the term supporting monomer refers to molecules with amolecular weight of less than approximately 1000 g/mol, and the termsupporting polymer is used for molecules with a molecular weight ofapproximately 1000 g/mol or more.

Generally the supporting monomer or polymer has a molecular weight inthe range of about 500 to about 100,000 g/mol, and preferably is apolymer with a molecular weight in the range of about 1,000 to about10,000 g/mol. Particularly good results were obtained with a supportingpolymer in the range of about 1,000 to about 6,000 g/mol. The number ofreactive groups per molecule of the supporting monomer or polymer ispreferably in the range of about 1.2 to about 64, more preferably in therange of about 1.2 to about 16, most preferably in the range of about1.2 to about 8.

The supporting monomer or polymer may be used in more than 0 wt % basedon the total weight of the dry coating, for example more than 10%, morethan 20 wt %, more than 30 wt % or more than 40 wt %. The supportingmonomer or polymer can be present in the hydrophilic coating formulationup to 90 wt %, however, more often the supporting monomer or polymerwill be used up to 50 or 60 wt %, based on the total weight of the drycoating.

The hydrophilic coating formulation according to the invention can forexample be cured using light visible or UV, electro-beam, plasma, gammaor IR radiation, optionally in the presence of a photoiniator or thermalinitiator, to form the hydrophilic coating. Examples of photoinitiatorsthat can be used in the hydrophilic coating are free-radicalphotoinitiators, which are generally divided into two classes accordingto the process by which the initiating radicals are formed. Compoundsthat undergo unimolecular bond cleavage upon irradiation are termedNorrish Type I or homolytic photoinitiators. A Norrish Type IIphotoinitiator interacts with a second molecule, i.e. a synergist, whichmay be a low molecular weight compound of a polymer, in the excitedstate to generate radicals in a bimolecular reaction. In general, thetwo main reaction pathways for Norrish Type II photoinitiators arehydrogen abstraction by the excited initiator or photoinduced electrontransfer. Examples of suitable free-radical photoinitiators aredisclosed in WO 00/18696 and are incorporated herein by reference.Preferred are photoinitiators are water-soluble or can be adjusted tobecome water-soluble, also preferred photoinitiators are polymeric orpolymerisable photoinitiators.

In one embodiment of the invention the polyelectrolyte is present in awetting fluid and introduced into the hydrophilic coating when wettingthe hydrophilic coating. This is particularly useful for medical deviceswith a hydrophilic coating which are packed in a fluid, or wherein thehydrophilic coating is wetted in a separate wetting fluid that containsthe polyelectrolyte. The invention therefore also relates to coatingsystem for preparing a lubricious coating, said coating systemcomprising a coating formulation comprising a non-ionic hydrophilicpolymer and a wetting fluid comprising a polyelectrolyte. Moreover theinvention relates to a coating system for preparing a lubriciouscoating, said coating system comprising a coating formulation accordingto the invention and a wetting fluid comprising a polyelectrolyte.

In one embodiment of the invention the hydrophilic coating formulationaccording to the invention further comprises at least one surfactant,which can improve the surface properties of the coating. Surfactantsconstitute the most important group of detergent components. Generally,these are water-soluble surface-active agents comprised of a hydrophobicportion, usually a long alkyl chain, attached to hydrophilic or watersolubility enhancing functional groups. Surfactants can be categorizedaccording to the charge present in the hydrophilic portion of themolecule (after dissociation in aqueous solution): ionic surfactants,for example anionic or cationic surfactants, and non-ionic surfactants.Examples of ionic surfactants include Sodium dodecylsulfate (SDS),Sodium cholate, Bis(2-ethylhexyl)sulfosuccinate Sodium salt,Cetyltrimethylammoniumbromide (CTAB), Lauryldimethylamine-oxide (LDAO),N-Lauroylsarcosine Sodium salt and Sodium deoxycholate (DOC). Examplesof non-ionic surfactants include Alkyl Polyglucosides such as TRITON™BG-10 Surfactant and TRITON CG-110 Surfactant, Branched SecondaryAlcohol Ethoxylates such as TERGITOL™ TMN Series, EthyleneOxide/Propylene Oxide Copolymers, such as TERGITOL L Series, andTERGITOL XD, XH, and XJ Surfactants, Nonylphenol Ethoxylates such asTERGITOL NP Series, Octylphenol Ethoxylates, such as TRITON X Series,Secondary Alcohol Ethoxylates, such as TERGITOL 15-S Series andSpecialty Alkoxylates, such as TRITON CA Surfactant, TRITON N-57Surfactant, TRITON X-207 Surfactant, Tween 80 and Tween 20.

Typically 0.001 to 1 wt % of surfactant is applied, preferably 0.05-0.5wt %, based on the total weight of the dry coating.

In one embodiment of the invention the hydrophilic coating formulationaccording to the invention further comprises at least one plasticizingagent, which can enhance the flexibility of the coating, which may bepreferable when the object to be coated is likely to bend during use.Said plasticizing agent may be included in the hydrophilic coatingformulation in a concentration of from about 0.01 wt % to about 15 wt %based on the total weight of the dry coating, preferably from about 1 wt% to about 5.0 wt %. Suitable plasticizers are high boiling compounds,preferably with a boiling point at atmospheric pressure of >200° C., andwith a tendency to remain homogeneously dissolved and/or dispersed inthe coating after cure. Examples of suitable plasticizers are mono- andpolyalcohols and polyethers, such as decanol, glycerol, ethylene glycol,diethylene glycol, polyethylene glycol and/or copolymers with propyleneglycol and/or fatty acids.

The invention also relates to a lubricious coating having an initiallubricity as measured on a Harland FTS Friction Tester of 20 g or less.

The hydrophilic coating according to the invention can be coated on anarticle. The hydrophilic coating can be coated on a substrate which maybe selected from a range of geometries and materials. The substrate mayhave a texture, such as porous, non-porous, smooth, rough, even oruneven. The substrate supports the hydrophilic coating on its surface.The hydrophilic coating can be on all areas of the substrate or onselected areas. The hydrophilic coating can be applied to a variety ofphysical forms, including films, sheets, rods, tubes, molded parts(regular or irregular shape), fibers, fabrics, and particulates.Suitable surfaces for use in the invention are surfaces that provide thedesired properties such as porosity, hydrophobicity, hydrophilicity,colorisability, strength, flexibility, permeability, elongation abrasionresistance and tear resistance. Examples of suitable surfaces are forinstance surfaces that consist of or comprise metals, plastics,ceramics, glass and/or composites. The hydrophilic coating may beapplied directly to the said surfaces or may be applied to a pretreatedor coated surface where the pretreatment or coating is designed to aidadhesion of the hydrophilic coating to the substrate.

In one embodiment of the invention the hydrophilic coating according tothe invention is coated on a biomedical substrate. A biomedicalsubstrate refers, in part, to the fields of medicine, and the study ofliving cells and systems. These fields include diagnostic, therapeutic,and experimental human medicine, veterinary medicine, and agriculture.Examples of medical fields include opthalmology, orthopedics, andprosthetics, immunology, dermatology, pharmacology, and surgery;nonlimiting examples of research fields include cell biology,microbiology, and chemistry. The term “biomedical” also relates tochemicals and compositions of chemicals, regardless of their source,that (i) mediate a biological response in vivo, (ii) are active in an invitro assay or other model, e.g., an immunological or pharmacologicalassay, or (iii) can be found within a cell or organism. The term“biomedical” also refers to the separation sciences, such as thoseinvolving processes of chromatography, osmosis, reverse osmosis, andfiltration. Examples of biomedical articles include research tools,industrial, and consumer applications. Biomedical articles includeseparation articles, implantable articles, and ophthalmic articles.Ophthalmic articles include soft and hard contact lenses, intraocularlenses, and forceps, retractors, or other surgical tools that contactthe eye or surrounding tissue. A preferred biomedical article is a softcontact lens made of a silicon-containing hydrogel polymer that ishighly permeable to oxygen. Separation articles include filters, osmosisand reverse osmosis membranes, and dialysis membranes, as well asbio-surfaces such as artificial skins or other membranes. Implantablearticles include catheters, and segments of artificial bone, joints, orcartilage. An article may be in more than one category, for example, anartificial skin is a porous, biomedical article. Examples of cellculture articles are glass beakers, plastic petri dishes, and otherimplements used in tissue cell culture or cell culture processes. Apreferred example of a cell culture article is a bioreactormicro-carrier, a silicone polymer matrix used in immobilized cellbioreactors, where the geometry, porosity, and density of theparticulate micro-carrier may be controlled to optimize performance.Ideally, the micro-carrier is resistant to chemical or biologicaldegradation, to high impact stress, to mechanical stress (stirring), andto repeated steam or chemical sterilization. In addition to siliconepolymers, other materials may also be suitable. This invention may alsobe applied in the food industry, the paper printing industry, hospitalsupplies, diapers and other liners, and other areas where hydrophilic,wettable, or wicking articles are desired.

The medical device can be an implantable device or an extracorporealdevice. The devices can be of short-term temporary use or of long-termpermanent implantation. In certain embodiments, suitable devices arethose that are typically used to provide for medical therapy and/ordiagnostics in heart rhythm disorders, heart failure, valve disease,vascular disease, diabetes, neurological diseases and disorders,orthopedics, neurosurgery, oncology, opthalmology, and ENT surgery.

Suitable examples of medical devices include, but are not limited to, astent, stent graft, anastomotic connector, synthetic patch, lead,electrode, needle, guide wire, catheter, sensor, surgical instrument,angioplasty balloon, wound drain, shunt, tubing, infusion sleeve,urethral insert, pellet, implant, blood oxygenator, pump, vasculargraft, vascular access port, heart valve, annuloplasty ring, suture,surgical clip, surgical staple, pacemaker, implantable defibrillator,neurostimulator, orthopedic device, cerebrospinal fluid shunt,implantable drug pump, spinal cage, artificial disc, replacement devicefor nucleus pulposus, ear tube, intraocular lens and any tubing used inminimally invasive surgery.

Articles that are particularly suited to be used in the presentinvention include medical devices or components such as catheters, forexample intermittent catheters, guidewires, stents, syringes, metal andplastic implants, contact lenses and medical tubing.

The hydrophilic coating formulation can be applied to the substrate byfor example dip-coating. Other methods of application include spray,wash, vapor deposition, brush, roller and other methods known in theart.

The concentration of ionic or ionizable groups in the hydrophiliccoating and the thickness of the hydrophilic coating according to theinvention may be controlled by altering the type of polyelectrolyte,polyelectrolyte concentration in the hydrophilic coating formulation,soaking time, drawing speed, viscosity of the hydrophilic coatingformulation and the number of coating steps. Typically the thickness ofa hydrophilic coating on a substrate ranges from 0.1-300 μm, preferably0.5-100 μm, more preferably 1-30 μm.

The invention further relates to a method of forming on a substrate ahydrophilic coating which has a low coefficient of friction when wettedwith a water-based liquid, wherein said hydrophilic coating comprises anpolyelectrolyte.

To apply the hydrophilic coating on the substrate, a primer coating maybe used in order to provide a binding between the hydrophilic coatingand the substrate. The primer coating is often referred to as theprimary coating, base coat or tie coat. Said primer coating is a coatingthat facilitates adhesion of the hydrophilic coating to a givensubstrate, as is described in for example WO02/10059. The bindingbetween the primer coating and the hydrophilic coating may occur due tocovalent or ionic links, hydrogen bonding, physisorption or polymerentanglements. These primer coatings may be solvent based, water based(latexes or emulsions) or solvent free and may comprise linear, branchedand/or crosslinked components. Typical primer coatings that could beused comprise for example polyether sulfones, polyurethanes, polyesters,including polyacrylates, as described in for example U.S. Pat. No.6,287,285, polyamides, polyethers, polyolefins and copolymers of thementioned polymers.

In particular, the primer coating comprises a supporting polymernetwork, the supporting network optionally comprising a functionalhydrophilic polymer entangled in the supporting polymer network asdescribed in WO06/056482 A1. The information with respect to theformulation of the primer coating is herewith incorporated by reference.

A primer layer as described above is in particular useful for improvingadherence of a coating comprising a hydrophilic polymer such as apolylactam, in particular PVP and/or another of the above identifiedhydrophilic polymers, in particular on polyvinylchloride (PVC),silicone, polyamide, polyester, polyolefin, such as polyethylene,polypropylene and ethylene-propylene rubber (e.g. EPDM), or a surfacehaving about the same or a lower hydrophilicity.

In an embodiment, the surface of the article is subjected to oxidative,photo-oxidative and/or polarizing surface treatment, for example plasmaand/or corona treatment in order to improve the adherence of the coatingwhich is to be provided. Suitable conditions are known in the art.

Application of the formulation of the invention may be done in anymanner. Curing conditions can be determined, based on known curingconditions for the photo-initiator and polymer or routinely bedetermined.

In general, curing may be carried out at any suitable temperaturedepending on the substrate, as long as the mechanical properties oranother property of the article are not adversely affected to anunacceptable extent.

Intensity and wavelength of the electromagnetic radiation can routinelybe chosen based on the photoinitiator of choice. In particular, asuitable wavelength in the UV, visible or IR part of the spectrum may beused.

The invention will be further illustrated by the following examples.

EXAMPLES

In the following examples hydrophilic coating formulations according tothe invention and comparative coating formulations have been applied toPVC tubings, as described below, and subsequently cured to formhydrophilic coatings according to the invention.

PVC Male Catheters

Uncoated PVC tubings were coated with a hydrophilic coating. The PVCtubing had a length of 23 cm, an outside diameter of 4.5 mm (14 Fr), andan inside diameter of 3 mm. The tubings were sealed on one side in orderto prevent the coating formulation to reach the inside of the tubingduring dipping.

Synthesis of PTGL1000(T-H)₂

In a dry inert atmosphere toluene diisocyanate (TDI or T, Aldrich, 95%purity, 87.1 g, 0.5 mol), Irganox 1035 (Ciba Specialty Chemicals, 0.58g, 1 wt % relative to hydroxy ethyl acrylate (HEA or H)) and tin(II)2-ethyl hexanoate (Sigma, 95% purity, 0.2 g, 0.5 mol) were placed in a 1liter flask and stirred for 30 minutes. The reaction mixture was cooledto 0° C. using an ice bath. HEA (Aldrich, 96% purity, 58.1 g, 0.5 mol)was added dropwise in 30 min, after which the ice bath was removed andthe mixture was allowed to warm up to room temperature. After 3 h thereaction was complete.Poly(2-methyl-1,4-butanediol)-alt-poly(tetramethyleneglycol) (PTGL,Hodogaya, M_(n)=1000 g/mol, 250 g, 0.25 mol) was added dropwise in 30min. Subsequently the reaction mixture was heated to 60° C. and stirredfor 18 h, upon which the reaction was complete as indicated by GPC(showing complete consumption of HEA), IR (displayed no NCO relatedbands) and NCO titration (NCO content below 0.02 wt %).

Primer Coating Formulation (Used in Examples 1-6 and ComparativeExamples A-D)

PTGL1000(T-H)₂ 4.25% (w/w) Polyvinylpyrollidon (1.3 M, Aldrich) (PVP)0.75% (w/w) Irgacure 2959 (Aldrich) 0.20% (w/w) Ethanol (Merck pa) 94.8%(w/w)

Primer Coating Formulation (Used in Example 7)

PTGL 1000(T-H)₂ 4.50% (w/w) Polyvinylpyrollidon (1.3 M, Aldrich) (PVP)0.50% (w/w) Irgacure 2959 (Aldrich) 0.20% (w/w) Ethanol (Merck pa) 94.8%(w/w)

Example 1 Hydrophilic Coating Formulation

Polyethylene glycol diacrylate (PEG4000DA) 5% (w/w) Polyethylene oxidewith M_(n) = 200,000 g/mol 3.75% (w/w) (PEG 200K) (Aldrich)Poly(acrylamide-co-acrylic acid) partial 1.25% (w/w) sodium salt (14.5wt % of Na⁺), 20 wt % acrylamide (PAcA) (Aldrich) Irgacure 2959 0.1%(w/w) Tween 80 (surfactant) (Merck) 0.01% (w/w) Distilled water 44.94%(w/w) Methanol (Merck pa) 44.95% (w/w)

Example 2 Hydrophilic Coating Formulation

PEG4000DA 5% (w/w) PEO 200K 3.75% (w/w) PAcA 1.25% (w/w) Irgacure 29590.1% (w/w) Distilled water 44.95% (w/w) Methanol 44.95% (w/w)

Example 3 Hydrophilic Coating Formulation

PVP 5% (w/w) PAcA 1.25% (w/w) Benzophenone 0.1% (w/w) Distilled water46.83% (w/w) Methanol 46.83% (w/w)

Example 4 Hydrophilic Coating Formulation

PEG4000DA 5% (w/w) PEO 200K 3.75% (w/w) Poly(acrylic acid) sodium salt1.25% (w/w) (Sigma-Aldrich, average Mw 30,000) Irgacure 2959 0.1% (w/w)Distilled water 44.95% (w/w) Methanol 44.95% (w/w)

Example 5 Hydrophilic Coating Formulation

PEG4000DA 5% (w/w) PEO 200K 3.75% (w/w) Polyacrylic acid-co-maleic acidsodium salt 1.25% (w/w) (Sigma-Aldrich, average Mw 70,000) Irgacure 29590.1% (w/w) Distilled water 44.95% (w/w) Methanol 44.95% (w/w)

Comparative Experiment A. Coating Formulation

PEG4000DA 5% (w/w) PEO 200K 5% (w/w) Irgacure 2959 0.1% (w/w) Distilledwater 44.95% (w/w) Methanol 44.95% (w/w)

Comparative Experiment B. Coating Formulation

PVP 5% (w/w) Benzophenone 0.1% (w/w) Distilled water 47.45% (w/w)Methanol 47.45% (w/w)

Example 6 Hydrophilic Coating Formulation

PEG4000DA 2% (w/w) PVP 1.33% (w/w) PAcA 0.67% (w/w) Irgacure 2959 0.04%(w/w) Tween 80 0.04% (w/w) Distilled water 47.96% (w/w) Methanol 47.96%(w/w)

Comparative Experiment C. Hydrophilic Coating Formulation

PEG4000DA 2% (w/w) PVP 2% (w/w) Irgacure 2959 0.04% (w/w) Tween 80 0.04%(w/w) Distilled water 47.96% (w/w) Methanol 47.96% (w/w)

Comparative Experiment D. Hydrophilic Coating Formulation

PEG4000DA 2% (w/w) PAcA 2% (w/w) Irgacure 2959 0.04% (w/w) Tween 800.04% (w/w) Distilled water 47.96% (w/w) Methanol 47.96% (w/w)

Example 7 Hydrophilic Coating Formulation Comprising Glycerol

PVP 5.50 wt % PAcA 0.75 wt % Benzophenon 0.12 wt % Glycerol 0.30 wt %Distilled water 46.67 wt % Methanol 46.67 wt %All ingredients were commercially obtained.

The coating obtained after curing the formulation of Example 7 is foundto be lubricious, to have a good dry-out time and adheres sufficientlyto the PVC catheter, also after gamma sterilisation. No visible cracksare observed by the naked eye.

Synthesis of PEG4000DA

150 g (75 mmol OH) of polyethyleneglycol (PEG, Biochemika Ultra fromFluka, OH value 28.02 mg KOH/g, 499.5 mew/kg, M_(n)=4004 g/mol) wasdissolved in 350 ml of dry toluene at 45° C. under nitrogen atmosphere.0.2 g (0.15 wt %) of Irganox 1035 was added as a radical stabilizer. Theresulting solution was distilled azeotropically overnight (50° C., 70mbar) leading the condensed toluene over 4 Å mol sieves. For each batchof PEG the OH value was accurately determined by OH titration, which wasperformed according to the method described in the 4^(th) edition of theEuropean Pharmacopoeia, paragraph 2.5.3, Hydroxyl Value, page 105. Thismade it possible to calculate the amount of acryloyl chloride to beadded and to determine the degree of acrylate esterification during thereaction. 9.1 g (90 mmol) of triethylamine was added to the reactionmixture, followed by a dropwise addition of 8.15 g (90 mmol) of acryloylchloride dissolved in 50 ml of toluene in 1 h. Triethylamine andacryloyl chloride were colorless liquids. The reaction mixture wasstirred for 2 to 4 h at 45° C. under nitrogen atmosphere. During thereaction the temperature was kept at 45° C. to prevent crystallizationof PEG. To determine the conversion a sample was withdrawn from thereaction mixture, dried and dissolved in deuterated chloroform.Trifluoro acetic anhydride (TFAA) was added and a ¹H-NMR spectrum wasrecorded. TFAA reacts with any remaining hydroxyl groups to form atrifluoro acetic ester, which can be easily detected using ¹H-NMRspectroscopy (the triplet signal of the methylene protons in theα-position of the trifluoro acetic acid group (g, 4.45 ppm) can beclearly distinguished from the signal of the methylene groups in theα-position of the acrylate ester (d, 4.3 ppm)). When the degree ofacrylate esterification was 98% an additional 10 mmol of acryloylchloride and triethylamine were added to the reaction mixture allowingit to react for 1 h. At a degree of acrylate esterification >98% thewarm solution was filtered to remove triethylamine hydrochloride salts.Approximately 300 ml of toluene was removed under vacuum (50° C., 20mbar). The remaining solution was kept at 45° C. in a heated droppingfunnel and added dropwise to 1 liter of diethyl ether (cooled in an icebath). The ether suspension was cooled for 1 h before the PEG diacrylateproduct was obtained by filtration. The product was dried overnight atroom temperature under reduced air atmosphere (300 mbar). Yield: 80-90%as white crystals.

Coating and Curing Process for Examples 1-7 and Comparative ExperimentsA-D

The PVC tubings were first dip-coated with the primer coatingformulation, and cured using a Harland PCX coater/175/24 according tothe dip protocol for the primer coating in Table 2. Subsequently thehydrophilic coating formulation was applied and cured using a HarlandPCX coater/175/24 according to the dip protocol for the hydrophiliccoating. The Harland PCX coater/175/24 was equipped with a HarlandMedical systems UVM 400 lamp. Intensity of the lamps of the Harland PCXcoater/175/24 was on average 60 mW/cm² and was measured using a SolatellSola Sensor 1 equipped with an International Light detector SED005#989,Input Optic: W#11521, filter: wbs320#27794. The IL1400A instructionmanual of International Light was applied, which is available on theinternet: www.intl-light.com. The UV dose was approximately 1.8 J/cm²for the primer coating and 21.6 J/cm² for the hydrophilic coating. Forapplied coating parameters see Table 1.

Visual inspection of the coated PVC tubings showed good wetting of thehydrophilic coating. A uniform coating was obtained.

TABLE 1 Applied coating parameters Coating parameters selection tableHydrophilic Dipping Cycle Primer coating coating Range Move device 125125 2 to 175 cm carrier to position Speed (cm/sec) 6.5 6.5 0.2 to 6.5cm/sec Acceleration 0.1 0.1 0.1 cm/sec/sec (sec) Move device 11.5 11.5 2to 175 cm carrier down Speed (cm/sec) 4 2 0.2 to 6.5 cm/sec Acceleration0.1 0.1 0.1 cm/sec/sec (sec) Move device 27.5 27.5 2 to 175 cm carrierdown Speed (cm/sec) 2 2 0.2 to 6.5 cm/sec Acceleration 0.1 0.1 0.1cm/sec/sec (sec) Time Pause 10 10 0 to 1800 sec Move device 28.5 28.5carrier up Speed (cm/sec) 0.3 1.5 (0.3 in 0.2 to 6.5 cm/sec Example 6and Comparative exp. C and D) Acceleration 0.1 0.1 0.1 cm/sec/sec (sec)Move device 148 148 2 to 175 cm carrier to position Speed (cm/sec) 6.56.5 0.2 to 6.5 cm/sec Acceleration 0.1 0.1 0.1 cm/sec/sec (sec) CureCycle Rotator On 2 2 1 to 8 rpm Time pause 30 (15 in 360 (180 in 0 to1800 sec Example 6 and Example 6 and Comparative Comparative Exp. C andD) Exp. C and D)

Test Methods Lubricity Test

Lubricity tests were performed on a Harland FTS5000 Friction Tester(HFT). The protocol was selected: see Table 2 for HFT settings. Frictiontester pads were used from Harland Medical Systems, P/N 102692, FTS5000Friction Tester Pads, 0.125*0.5**0.125, 60 durometer.

Subsequently the desired test description was inserted when “run test”was activated. After inserting a guidewire into the catheter, thecatheter was attached in the holder. The device was adjusted down to thedesired position such that the catheter was soaked in demineralizedwater for 1 min. After zero gauging in water the protocol was activatedby pushing “start”. The data were saved after finishing. The holder wasremoved from the force gauge and subsequently the catheter was removedfrom the holder.

TABLE 2 HFT settings Transport movement (cm) 10 Clamp force (g) 300 Pullspeed (cm/s) 1 Acceleration time (s) 2 Number of cycles 25

Dry-Out Time

Dry-out time is herein defined as the duration of the coating remaininglubricious after the device has been taken out of the wetting fluidwherein it has been stored and/or wetted. Dry-out time can be determinedby measuring the friction in grams as a function of time the catheterhas been exposed to air on the HFT (see above). The dry-out time is thepoint in time wherein the friction reaches a value of 20 g or higher, orin a stricter test 15 g or higher as measured at a temperature of 22° C.and 35% relative humidity. After inserting the guidewire into the coatedPVC male catheter, the catheter was attached in the holder. The catheterwas soaked in demineralized water for 1 min. The holder with thecatheter was put in the force gauge and the device was jogged down tothe desired position and the test was started immediately according tothe same settings as for the lubricity test. Measurements were performedafter 1, 2, 5, 7.5, 10, 12.5 and 15 minutes. The friction tester padswere cleaned and dried after each measurement. The data were saved afterfinishing. The holder was removed from the force gauge and subsequentlythe catheter was removed from the holder.

In Table 3 the lubricity as a function of time of the lubricious coatingprepared according to Examples 1-5 is given, as well as the results ofComparative Experiments A and B.

TABLE 3 Lubricity as a function of time of the lubricious coatingprepared according to Examples 1-5 and Comparative Experiments A-B.Dry-out time: friction (g) in air as function of time (min) 1 min 2 min5 min 7.5 min 10 min 12.5 min 15 min Example 1 7.7 9.3 9.5 10.5 12.115.6 20.8 Example 2 13.0 15.8 21.6 26.6 35.7 61.0 58.6 Example 3 11.013.8 15.2 15.6 16.1 16.9 18.1 Example 4 12 17 67 Example 5 11 14 53Compar- 26.1 31.2 41.8 68.4 187.1 238.7 ative Exp. A Compar- 21.3 24.154.6 87 193 ative Exp. B

The Table shows that the lubricity is significantly higher (i.e. thefriction is lower) for the lubricious coatings according to theinvention (Examples 1-5), comprising poly(acrylamide-co-acrylic acid)partial sodium salt, poly(acrylic acid) sodium salt or poly(acrylicacid-co-maleic acid) sodium salt, than for the lubricious coatings ofComparative Experiments A and B which do not comprise a polyelectrolyte.The lubricious coating according to the invention remained lubriciousfor a much longer period in the dry-out test than the coatings of thecomparative examples.

In Table 4 the lubricity of the lubricious coatings prepared accordingto Example 6 and the Comparative Experiments C and D is given.

TABLE 4 Lubricity of the lubricious coating prepared according toExample 6 and Comparative Experiments C-D. Lubricity: friction (g) underwater Initial (1 cycle) End (25 cycles) Example 6 1.6 2.4 ComparativeExp. C 5.1 5.8 Comparative Exp. D 52 434 (after 4 cycles)

The Table shows that the coatings according to Example 6 are morelubricious (i.e. lower friction values) than the coatings according toComparative Experiment C, which involves a coating formulationcomprising a non-ionic hydrophilic polymer, but no polyelectrolyte, orExample D, which involves a coating formulation comprising apolyelectrolyte, but no non-ionic hydrophilic polymer.

The results of the lubricity measurements as a function of time (Table3) and the lubricity measurements show that the combination of apolyelectrolyte and a non-ionic hydrophilic polymer results in a highlubricity and a high dry-out time of the coating.

1. Hydrophilic coating formulation which when cured results in ahydrophilic coating, wherein the hydrophilic coating formulationcomprises a polyelectrolyte and a non-ionic hydrophilic polymer. 2.Hydrophilic coating formulation according to claim 1, wherein thepolyelectrolyte is chosen from the group consisting of salts of homo-and copolymers of acrylic acid, salts of homo- and co-polymers ofmethacrylic acid, salts of homo- and co-polymers of maleic acid, saltsof homo- and co-polymers of fumaric acid, salts of homo- and co-polymersof monomers comprising sulfonic acid groups, homo- and co-polymers ofmonomers comprising quarternary ammonium salts and mixtures and/orderivatives thereof.
 3. Hydrophilic coating formulation according toclaim 1, wherein the polyelectrolyte is a copolymeric polyelectrolyte,wherein the copolymeric polyelectrolyte is a copolymer comprising atleast two different types of constitutional units, wherein at least onetype of constitutional units comprises ionizable or ionized groups andat least one type of constitutional units is absent of ionizable orionized groups.
 4. Hydrophilic coating formulation according to claim 1,wherein the polyelectrolyte is selected from the group consisting ofpoly(acrylamide-co-acrylic acid) salts, a poly(methacrylamide-co-acrylicacid) salts, a poly(acrylamide-co-methacrylic acid) salts,poly(methacrylamide-co-methacrylic acid) salts, apoly(acrylamide-co-maleic acid) salts, poly(methacrylamide-co-maleicacid) salts, poly(acrylamide-co-dialkylammoniumchloride) orpoly(methacrylamide-co-dialkylammoniumchloride).
 5. Hydrophilic coatingformulation according to claim 1, wherein the non-ionic hydrophilicpolymer is selected from the group consisting of poly(lactams), forexample polyvinylpyrollidone (PVP), polyurethanes, homo- and copolymersof acrylic and methacrylic acid, polyvinyl alcohol, polyvinylethers,maleic anhydride based copolymers, polyesters, vinylamines,polyethyleneimines, polyethyleneoxides, poly(carboxylic acids),polyamides, polyanhydrides, polyphosphazenes, cellulosics, for examplemethyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, andhydroxypropylcellulose, heparin, dextran, polypeptides, for examplecollagens, fibrins, and elastin, polysaccharides, for example chitosan,hyaluronic acid, alginates, gelatin, and chitin, polyesters, for examplepolylactides, polyglycolides, and polycaprolactones, polypeptides, forexample collagen, albumin, oligo peptides, polypeptides, short chainpeptides, proteins, and oligonucleotides.
 6. Hydrophilic coatingformulation according to claim 1, the hydrophilic coating formulationfurther comprising a supporting monomer and/or polymer, which comprisesa plurality of reactive moieties capable of undergoing cross-linkingreactions.
 7. Hydrophilic coating formulation according to claim 6,wherein the supporting monomer and/or polymer is a hydrophilicsupporting monomer and/or polymer.
 8. Hydrophilic coating formulationaccording to claim 1, the hydrophilic coating formulation furthercomprising at least one surfactant.
 9. Hydrophilic coating formulationaccording to claim 1, the hydrophilic coating formulation furthercomprising at least one plasticizer.
 10. Hydrophilic coating obtainableby curing a hydrophilic coating formulation according to claim
 1. 11.Lubricious coating obtainable by applying a wetting fluid to ahydrophilic coating according to claim
 10. 12. Lubricious coating havingan initial lubricity after 1 cycle as measured on a Harland FTS FrictionTester of 20 g or less.
 13. Lubricious coating according to claim 11having an initial lubricity after 1 cycle as measured on a Harland FTSFriction Tester of 20 g or less.
 14. Coating system for preparing alubricious coating, said coating system comprising a coating formulationcomprising a non-ionic hydrophilic polymer and a wetting fluidcomprising a polyelectrolyte.
 15. Coating system for preparing alubricious coating, said coating system comprising a coating formulationaccording to claim 1 and a wetting fluid comprising a polyelectrolyte.16. Use of a polyelectrolyte and a non-ionic hydrophilic polymer in alubricious coating in order to improve the dry-out time of thelubricious coating, wherein dry-out time is defined as the duration ofthe coating remaining lubricious after a device comprising thelubricious coating has been taken out of the wetting fluid wherein ithas been stored and/or wetted, which is determined by measuring thefriction in g as a function of time on a Harland FTS Friction Tester.17. Article comprising at least one hydrophilic coating or lubriciouscoating according to claim
 10. 18. Article according to claim 17,wherein the article is a medical device or component.
 19. Medical deviceor component according to claim 18 comprising a catheter, a medicaltubing, a guidewire, a stent, or a membrane.
 20. Method of forming on asubstrate a hydrophilic coating, the method comprising applying ahydrophilic coating formulation according to claim 1 to at least onesurface of the article; and allowing the coating formulation to cure byexposing the formulation to electromagnetic radiation thereby activatingthe initiator.